To insinuate means to suggest something negative or critical in an indirect, subtle way rather than stating it openly. When someone insinuates, they hint at an idea without saying it directly, often planting a suggestion in a sneaky or underhanded manner.

Imagine a classmate saying, “I noticed you got a perfect score on the test, and you were sitting right next to the smartest kid in class.” They haven't directly accused you of doing anything wrong, but they're insinuating it. That's what makes insinuation so frustrating: the person suggests something unfair or unkind while insisting they “didn't actually say that.”

People also use insinuate to describe physically sliding into a tight space. A cat might insinuate itself through a barely open door, or you might insinuate your hand into a narrow opening to retrieve something.